The present invention relates to foam-in-place packaging and, more particularly, to a simplified and improved apparatus and process for producing foam-in-place packaging cushions and other flexible, fluid-filled containers.
Foam-in-place packaging is a highly useful technique for on-demand protection of packaged objects. In its most basic form, foam-in-place packaging comprises injecting foamable compositions from a dispenser into a container that holds an object to be cushioned. Typically, the object is wrapped in plastic to keep it from direct contact with the rising (expanding) foam. As the foam rises, it expands into the remaining space between the object and its container (e.g. a corrugated board box) thus forming a custom cushion for the object.
A common foamable composition is formed by mixing an isocyanate compound with a hydroxyl-containing material, such as a polyol (i.e., a compound that contains multiple hydroxyl groups), typically in the presence of water and a catalyst. The isocyanate and polyol precursors react to form polyurethane. At the same time, the water reacts with the isocyanate compound to produce carbon dioxide. The carbon dioxide causes the polyurethane to expand into a foamed cellular structure, i.e., a polyurethane foam, which serves to protect the packaged object.
In other types of foam-in-place packaging, an automated apparatus produces flexible bags or other containers from flexible, plastic film and dispenses a foamable composition into the bags as the bags are being formed. As the composition expands into a foam within the bag, the bag is sealed shut and typically dropped into a container holding the object to be cushioned. The rising foam again tends to expand into the available space, but does so inside the bag. Because the bags are formed of flexible plastic, they form individual custom foam cushions around the packaged objects. Exemplary types of such packaging apparatus are assigned to the assignee of the present invention, and are illustrated, for example, in U.S. Pat. Nos. 4,800,708, 4,854,109, 5,027,583, 5,376,219, and 6,003,288, the contents of each of which are incorporated entirely herein by reference.
As will be noted from the foregoing patents, conventional packaging apparatus for forming a foam-in-place cushions begin with a plastic film and convert the film into bags (for containment of the foamable composition) through the use of various heat-seal devices. That is, two plies of plastic film material are generally heat-sealed together both transversely and longitudinally as they are being fed from a stock supply to form a generally rectangular bag with the foam inside. In alternative embodiments, the stock supply of plastic film material can be fed in center-folded fashion so that one side of the bag is a fold, rather than a heat seal. Nevertheless, the other three sides of the bag must formed in-line by the packaging machine through the use of two or more heat-sealing devices.
Such conventional foam-in-place packaging apparatus have gained rapid and wide acceptance in the marketplace and have served their purposes well. However, improvement of such apparatus is continually sought. One aspect in which improvement is desired concerns the complexity of such apparatus, particularly with regard to the various heat seals that must be formed in order to convert the stock film into bags for containment of the foamable composition. Generally, one or two heat seal devices are needed to form longitudinal heat seals while a different type of heat seal device is needed to form transverse heat seals. In addition, as each bag is filled and sealed, the resultant completed foam-in-place cushion must be severed from the film. This is typically done with the application of sufficient heat to melt completely through the plastic.
Accordingly, there is a need in the art for a simpler and less expensive foam-in-place packaging apparatus that does not require two or more different types of heat-seal devices and a severing device. Such apparatus would require far less maintenance than conventional foam-in-place packaging apparatus and would be affordable to smaller companies. A simple but effective means for automating foam-in-place packaging apparatus is also needed.
Those needs are met by the present invention, which, in one aspect, provides an apparatus for dispensing fluid into pre-formed, flexible containers and enclosing the fluid within the containers, comprising:
a. a web of film comprising a series of pre-formed flexible containers, each of the pre-formed containers being capable of holding therein a quantity of fluid and having an opening for receiving such fluid;
b. a mechanism that conveys the film web along a path of travel;
c. a dispenser through which fluid may flow in predetermined amounts, the dispenser being positioned adjacent the travel path of the film web such that the dispenser is capable of dispensing fluid into the pre-formed containers via the openings therein; and
d. a device for sealing closed the opening in each of the pre-formed containers to thereby enclose fluid held within the containers.
The use of pre-formed containers greatly simplifies and reduces the cost of the above-described apparatus, in that only the opening of the container needs to be sealed closed by the apparatus.
Preferably, each of the pre-formed containers are manually detachable from the film web along one or more lines of weakness.
Another aspect of the invention is a method for dispensing fluid into pre-formed, flexible containers and enclosing the fluid within the containers, comprising:
a. supplying a web of film comprising a series of pre-formed flexible containers, each of the pre-formed containers being capable of holding therein a quantity of fluid and having an opening for receiving such fluid;
b. conveying the film web along a predetermined path of travel;
c. dispensing fluid into the pre-formed containers via the openings therein; and
d. sealing closed the opening in each of the pre-formed containers to thereby enclose fluid held within the containers.
A further aspect of the invention is an automated apparatus for dispensing fluid into flexible containers and enclosing the fluid within the containers, comprising:
a. a web of film comprising two juxtaposed plies of plastic film that define a partially-formed flexible container, the film web also comprising one or more indicators thereon;
b. a mechanism that conveys the film web along a path of travel;
c. a dispenser through which fluid may flow in predetermined amounts, the dispenser being positioned adjacent the travel path of the film web such that the dispenser can dispense fluid product into the partially-formed flexible container;
d. a sensing device capable of detecting the one or more indicators on the film web and generating an output signal upon detection of the one or more indicators;
e. a control device capable of receiving the output signal from the sensing device as an input signal and, based at least in part on the input signal, controlling the conveyance of the film web and dispensation of fluid into the pre-formed containers; and
f. one or more devices for sealing the plies of plastic film together to complete the partially-formed container, thereby enclosing the fluid product therein.
These and other aspects and features of the invention may be better understood with reference to the following description and accompanying drawings.